CN108988897B

CN108988897B - Railway LTE-R wireless communication terminal equipment

Info

Publication number: CN108988897B
Application number: CN201810827439.XA
Authority: CN
Inventors: 刘宇峰; 杨胜; 付忠良; 朱海彬
Original assignee: Shenzhen Sed Wireless Communication Technology Co ltd
Current assignee: Shenzhen Sed Wireless Communication Technology Co ltd
Priority date: 2018-07-25
Filing date: 2018-07-25
Publication date: 2021-07-06
Anticipated expiration: 2038-07-25
Also published as: CN108988897A

Abstract

The invention provides railway LTE-R wireless communication terminal equipment, which comprises an LTE-R signal transceiver module, a secondary power amplification circuit module, a duplex module and a receiving access module which are sequentially connected; the LTE-R signal transceiver module is used for transmitting and receiving signals; the secondary power amplifying circuit module is used for amplifying the power of the circuit; the duplex module is used for isolating the transmitting signal from the receiving signal and ensuring that the transmitting and receiving can work normally at the same time; the receiving access module is used for feeding back the received signal to the LTE-R signal transceiver module. In the invention, under the condition of increasing the signal from 200mW to 2W, the adjacent channel leakage ratio, the EVM error vector magnitude, the SEM frequency spectrum emission wave cover and other linear indexes still ensure good characteristics, the 2W uplink power is more suitable for long-distance and high-speed scenes such as railways, and the isolation performance of emission to reception is well ensured.

Description

Railway LTE-R wireless communication terminal equipment

Technical Field

The invention relates to the technical field of wireless communication, in particular to railway LTE-R wireless communication terminal equipment.

Background

In recent decade, with the rapid development of railways in China, the GSM-R system (a comprehensive dedicated digital mobile communication system specially designed for railway communication) has been widely used in each railway line. Meanwhile, the demands of a plurality of new railway services are continuously emerging, GSM-R belongs to a narrow-band communication system, as a second-generation mobile communication technology, the frequency spectrum utilization rate is low, voice services and a small amount of data services are mainly carried, the data rate is low, the circuit domain data services are generally only 2400-9600 bit/s, the rate of the packet domain data services can only reach more than 100 Kbit/s, the difficulty of carrying broadband services such as video monitoring, video conferences, railway passenger mobile information services and the like on the existing GSM-R platform is very high, the public mobile communication network is developed from 2G to 3G and 4G, and the GSM market is atrophied. The international railroad association (UIC) explicitly states on the seventh world high speed rail congress called for in 12 months 2010: the long-term evolution of the high-speed railway mobile communication adopts the technical development strategy of a railway broadband mobile communication system (LTE-R). The high-speed railway communication can directly develop the standard 4G LTE-R technology from the 2G GSM-R technology to the 3G. Compared with the GSM-R, the LTE-R has advantages in the aspects of spectrum utilization rate, service rate, transmission delay and the like, and the evolution from the GSM-R to the LTE-R becomes necessary.

At present, the railway standard of LTE-R does not specify a specific frequency band, and for the frequency spectrum characteristic, a high frequency spectrum has a larger bandwidth, so that higher transmission flow can be provided to facilitate the improvement of the transmission rate, and a low frequency spectrum can provide longer-distance coverage. If the LTE-R operates in the high frequency spectrum, the requirement for the density of base station establishment is high, because the high frequency spectrum has high propagation loss and severe information receiving and fading, the distance between the LTE-R base stations must be less than 2 km, which results in an increase in the number of base stations, a sharp increase in investment cost, and frequent switching of frequencies between the base stations. Low frequency spectra such as 450-470 MHz, 800-900 MHz, and 1.4GHz are also widely considered for LTE-R use. Taking China as an example, 450-470 MHz is used for communication of departments such as central party administration, army, railway, public security and the like and communication frequency of command and dispatch systems of some enterprises and public institutions. 450MHz has low frequency band, small transmission loss and strong diffraction capability, and can cover a larger range by adopting the same number of base stations. Under the same transmission power and propagation conditions, the FDD-LTE technology is operated, the coverage distance of 450MHz is about 3.5 times of 1.8GHz, the number of base stations required by using a 450MHz frequency band is only 8.3% of 1.8GHz when the mobile communication network covers the same area, and the mobile communication network is very suitable for railway communication construction, so that the LTE-R is operated by using 450-470 MHz in the evaluation of the Chinese railway bureau.

Under the current situation, an LTE-R module of 450MHz is produced, but the LTE-R modules in the market all have a transmission power of about 250mW or less, and for the vehicle-mounted module, the power is relatively low, because the power of the base station is much greater than that of the mobile phone, if the mobile phone is far away from the base station, the uplink signal of the mobile phone cannot be analyzed if the uplink signal is not enhanced, the uplink power of the LTE-R is relatively low, the uplink and downlink coverage of the system is unbalanced, and particularly in the case of a high-speed railway, single pass, poor quality, call drop and the like of the signal are caused.

Disclosure of Invention

The invention aims to solve the problems of single-pass signal, poor quality, call drop and the like caused by low uplink power of LTE-R, unbalanced uplink and downlink coverage of a system and high-speed railway conditions in the prior art.

In order to solve the technical problem, the invention provides railway LTE-R wireless communication terminal equipment, which comprises an LTE-R signal transceiver module, a secondary power amplification circuit module, a duplex module and a receiving access module which are sequentially connected; the LTE-R signal transceiver module is used for transmitting and receiving signals; the secondary power amplifying circuit module is used for amplifying the power of the circuit; the duplex module is used for isolating the transmitting signal from the receiving signal and ensuring that the transmitting and receiving can work normally at the same time; the receiving access module is used for feeding back the received signal to the LTE-R signal transceiver module.

Preferably, the circuit further comprises a primary driver amplifier circuit, which is arranged between the LTE-R signal transceiver module and the secondary power amplification circuit module, and is used for amplifying a signal of the circuit to further ensure the linearity of the signal.

Further preferably, the secondary power amplifying circuit comprises an amplifying link gain control part, a power amplifying circuit part, a power coupling detection part and a power analyzing circuit part which are connected in sequence; the amplification link gain control part is used for carrying out accurate signal intensity control on signals of a preceding stage circuit, preventing distortion and burning, and controlling the gain performance of the whole link; the power amplifier circuit part is used for amplifying signals; the power coupling detection part is used for protecting the signal stability of the output end of the power amplifier tube and coupling detection power; the power analysis circuit part is used for sampling and analyzing the monitored power and feeding back a control command to the amplification link gain control part to adjust the link gain.

Furthermore, the power amplifier circuit part is realized by adopting LDMOS, and can amplify signals to 2W or above; a 2W LTE-R duplexer is adopted in the duplex module; the first-stage driving amplifier circuit is realized by a CLASS 3PA output module, and other duplexers with consistent or better performance can also be adopted.

Further, the amplification chain gain control part comprises an attenuator for adjusting the signal intensity in the circuit; the duplex module comprises an isolator and a duplexer which are connected in sequence and used for effectively isolating transmitting signals and receiving signals of the circuit.

Further, the wireless communication terminal equipment adopts an FDD-LTE frequency division duplex communication system.

Furthermore, the railway LTE-R terminal equipment of the TDD-LTE time division duplex communication system comprises an LTE-R signal transceiver module, a primary driving amplifier circuit module, a gain control module, a secondary power amplification circuit module and an antenna switch module which are sequentially connected. The LTE-R signal transceiver module is used for amplifying a signal of a circuit; the first-stage drive amplifier circuit is used for amplifying a signal of the circuit and ensuring the linearity of the signal; the gain control module is used for amplifying the gain of the circuit; the secondary power amplifying circuit module is used for amplifying the power of the circuit; the antenna switch module is used for opening or breaking a circuit signal.

Furthermore, the device also comprises a temperature detection circuit module, a power detection and analysis circuit module and a voltage monitoring and alarming module which are connected in parallel. The temperature detection circuit module is used for detecting the temperature of the circuit; the power detection and analysis circuit module is used for detecting the power of the circuit; the voltage monitoring alarm module is used for monitoring the voltage of the circuit.

Compared with the prior art, the invention has the beneficial effects that: in the aspect of improving the power of the LTE-R terminal, the effect is obvious, and the performance is improved. Under the condition of improving the signal from 200mW to 2W, the linear indexes of adjacent channel leakage ratio, EVM (error vector magnitude), SEM (spectrum emission wave cover) and the like still ensure good characteristics, and the limit requirement of 3GPP 36521.1 at the maximum power is met. Meanwhile, the 2W uplink power is more suitable for the application in long-distance and high-speed scenes such as railways. In the aspect of receiving performance, due to the adoption of the design of an isolator, a high-power duplexer and the like, the isolation performance of transmitting to receiving is well guaranteed, the sensitivity can reach-98 dBm under the bandwidth of 5MHz, and the requirement of 3GPP specification is completely met.

Further, harmonic suppression: the amplification device not only amplifies the original harmonic signal, but also generates harmonic due to nonlinear characteristics, so that harmonic suppression is an important index of an amplification system. In the embodiment of the invention, the attenuator, the isolator and the like are added in the design module, so that the harmonic performance is effectively inhibited, and the harmonic performance meets the requirement after the matching optimization of each link. Therefore, on the basis of 0.2W LTE-R, 2W or higher uplink power is achieved through the embodiment, and the performance after amplification meets the limitation requirement of 3GPP at the maximum power, so that the LTE-R system can be better applied and developed.

Drawings

FIG. 1 is a structural diagram of an LTE-R terminal system according to an embodiment of the present invention

FIG. 2 is a circuit diagram of a two-stage power amplifier of an embodiment of the invention;

FIG. 3 is a circuit diagram of an amplified link gain control circuit according to an embodiment of the present invention;

FIG. 4 is a diagram of a power amplifier circuit and a power coupling detection circuit according to an embodiment of the present invention;

FIG. 5 is a circuit diagram of a duplex module of an embodiment of the invention;

fig. 6 is a structure diagram of a TDD-LTE high-speed rail LTE-R terminal system according to an embodiment of the present invention;

1-isolator 2-duplexer 3-receive path 4-antenna end.

Detailed Description

In this embodiment, an LTE-R wireless terminal device meeting the requirements of the operation of the chinese railway is designed, and the frequency range is 452.5-457.5MHz for the uplink and 462.5-467.5MHz for the downlink with reference to the Band 31 frequency Band defined in the latest version 3GPP TS 136521-1R 14. When the performance requirement of the specification in the maximum power state is met, the CLASS 3 grade output by the LTE-R standard is improved to the power grade of 2W, so that the stability and the goodness of high-speed rail communication are ensured. Since the frequency band belongs to FDD (one of full duplex communication technologies used in mobile communication systems), the structure diagram of the LTE-R terminal system is shown in fig. 1, and includes an LTE-R signal transceiver module, a secondary power amplification circuit module, a duplex module, and a receiving path module, which are connected in sequence; the LTE-R signal transceiver module is used for transmitting and receiving signals; the secondary power amplifying circuit module is used for amplifying the power of the circuit; the duplex module is used for isolating the transmitting signal from the receiving signal and ensuring that the transmitting and receiving can work normally at the same time; the receiving access module is used for feeding back the received signal to the LTE-R signal transceiver module.

In fig. 1, a first-stage driving amplifier circuit may be further added, and the first-stage driving amplifier circuit is disposed between the LTE-R signal transceiver module and the second-stage power amplifier circuit module, so as to amplify the signal of the circuit and ensure good linearity of the amplified signal. The LTE-R transceiver module mainly modulates and demodulates LTE-R signals, modulates IQ signals of the LTE-R to a transmitting frequency band, and demodulates received signals of the LTE-R into IQ signals. The first-stage driving amplification module is mainly responsible for carrying out proper amplification processing on the LTE-R signal, and the LTE-R signal has higher peak-to-average ratio, so that the part needs to be increased to ensure the linearity of a next-stage amplification circuit.

After the LTE-R signal is amplified by the preceding stage, in order to ensure accurate and controllable gain of the link and power detection, as shown in fig. 2, the secondary power amplifying circuit includes an amplifying link gain control portion, a power amplifying circuit portion, a power coupling detection portion and a power analyzing circuit portion, which are connected in sequence; the amplification link gain control part is mainly used for carrying out accurate signal intensity control on signals of a preceding stage circuit, preventing distortion or burnout and controlling the gain performance of the whole link; the power amplifier circuit part belongs to a main amplifying part and is used for amplifying signals to 2W or above; the implementation case is realized by adopting the LDMOS; the power coupling detection part is used for protecting the signal stability of the output end of the power amplifier tube and coupling detection power; the power analysis circuit part is used for sampling and analyzing the monitored power and feeding back a control command to the amplification link gain control part to adjust the link gain. The conventional LTE system Power is Power CLass 3PA, namely 23dBm, and the primary drive amplifier circuit is realized by a CLass 3PA output module.

The LTE-R transceiver generates a Band 31 signal working at 450MHz through modulation, but the signal intensity is low at the moment and is below 5dBm, the power can reach 23dBm after primary driving amplification, which is equivalent to the performance requirement of LTE in standard 3GPP specifications, and the power is pushed to 33dBm through a secondary amplification module. And finally, transmitting the LTE transmitting signal to an antenna port through a high-power duplexer.

As shown in fig. 3, the amplifier chain gain control circuit includes an attenuator for adjusting the signal strength in the circuit.

As shown in fig. 4, the power amplifier circuit and the power coupling detection circuit amplify the LTE-R signal to a power level of 2W on the premise of ensuring good linearity, wherein the coupling circuit is used for power detection. In addition to the main operational modules in the above section, the impedance matching elements between the modules play a crucial role in the whole rf link, and may even determine whether the system is operating properly.

In order to amplify the LTE-R signal to 2W or more, a 2W LTE-R duplexer or another duplexer with the same or better performance may be used in the duplex module of this embodiment. There are three major problems we need to face: the three problems of high gain, high linearity and high isolation all put high requirements on the amplifier, and firstly, the high gain and high linearity need to be satisfied, and because the modulation modes of LTE and GSM are different, enough power back-off must be reserved to ensure enough peak-to-average power ratio. The power back-off of more than 10-15dBm is needed, and the gain of the selected amplifier needs to be about 20dB, so that good linearity can be kept. Secondly, the requirement of high isolation of the duplexer is met, because FDD-LTE signals are transmitted and received at the same time, the transmitting performance can seriously affect the receiving performance when the isolation is not enough, and the sensitivity is greatly reduced. Meanwhile, the power capacity of a conventional duplexer can only reach about 0.3W, and if a 2W input signal duplexer can be burnt out due to failure, the duplexer needs to be selected and considered. The design target is that the power is 33 +/-2.7 dBm, and indexes such as ACLR, SEM, frequency error and EVM and the like meet the limit requirement of 3GPP 36521.1 for maximum power.

As shown in fig. 5, is a circuit portion of a duplex module that includes an isolator and a duplexer connected in series to effectively isolate the transmit and receive signals of the circuit. The duplexer in the circuit ensures the characteristics of large input dynamic range, high port isolation and the like, and can realize high-performance long-term operation under the 2W input condition.

The embodiment of the invention adopts non-signaling verification and signaling verification. Non-signaling verification test is carried out at 450MHz, and an analog input signal is generated by using a signal source, wherein the specific test data is as follows: when VGG is 4V and VDD is 12.5V, the test data is as follows:

when 2dBm is input, the output power of the duplexer is 34.3dBm, the power of a receiving end is-27.2 dBm, and the isolation degree is about 60 dB.

After the whole system is built and verified, the LTE signaling test is started, and the CMW500 is used for testing. Supply voltage: the LTE module is powered by a power supply, and when VGG is 3.8V and VDD is 12.5V, the current: the power supply is about 500mA, the VDD terminal is 1.6A, and the test data are as follows:

the above test data completely meet the expected target, especially when the power level reaches 2W, the linear indexes such as SEM and ACLR are still at good level, and from the viewpoint of the sensitivity index, the isolation performance has good performance, so that the feasibility of the scheme can be proved.

The embodiment of the invention finally obtains very remarkable performance, and has obvious effect and improved performance in the aspect of improving the power of the LTE-R terminal. Under the condition of improving the signal from 200mW to 2W, the linear indexes of adjacent channel leakage ratio, EVM (error vector magnitude), SEM (spectrum emission wave cover) and the like still ensure good characteristics, and the limit requirement of 3GPP 36521.1 at the maximum power is met. Meanwhile, the 2W uplink power is more suitable for the application in long-distance and high-speed scenes such as railways. In the aspect of receiving performance, due to the adoption of the design of an isolator, a high-power duplexer and the like, the isolation performance of transmitting to receiving is well guaranteed, the sensitivity can reach-98 dBm under the bandwidth of 5MHz, and the requirement of 3GPP specification is completely met.

In terms of harmonic suppression: the amplification device not only amplifies the original harmonic signal, but also generates harmonic due to nonlinear characteristics, so that harmonic suppression is an important index of an amplification system. In the embodiment of the invention, the attenuator, the isolator and the like are added in the design module, so that the harmonic performance is effectively inhibited, and the harmonic performance meets the requirement after the matching optimization of each link.

Therefore, on the basis of the LTE-R of 0.2W, the uplink power of 2W is achieved through the embodiment of the aspect, and the performance after amplification meets the limitation requirement of the 3GPP at the maximum power, so that the LTE-R system can be better applied and developed.

The embodiment is used for an FDD-LTE (frequency division duplex) communication system, and on the basis, the invention also discloses a high-speed rail LTE-R terminal device of a TDD-LTE time division duplex communication system, which comprises an LTE-R signal transceiver module, a primary driving amplifier circuit module, a gain control module, a secondary power amplification circuit module and an antenna switching device module which are sequentially connected. The LTE-R signal transceiver module is used for amplifying a signal of a circuit; the first-stage drive amplifier circuit is used for amplifying a signal of the circuit and ensuring the linearity of the signal; the gain control module is used for amplifying the gain of the circuit; the secondary power amplifying circuit module is used for amplifying the power of the circuit; the antenna switch module is used for opening or breaking a circuit signal. The embodiment also comprises a temperature detection circuit module, a power detection and analysis circuit module and a voltage monitoring and alarming module which are connected in parallel; the temperature detection circuit module is used for detecting the temperature of the circuit; the power detection and analysis circuit module is used for detecting the power of the circuit; the voltage monitoring alarm module is used for monitoring the voltage of the circuit. The second embodiment is different from the first embodiment in that the duplex mode is changed, an original analog duplex device is replaced by an electronic switch device, the antenna switch type selection also needs to pay attention to the characteristics of input dynamic range, isolation, ESD, time delay and the like, the whole working principle is not changed, and the embodiment of the invention is mainly used for the railway communication market.

The present invention has been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made by those skilled in the art without departing from the spirit of the present invention based on the knowledge of the skilled person.

Claims

1. A railway LTE-R wireless communication terminal device, comprising: the system comprises a 0.2W LTE-R signal transceiver module, a secondary power amplification circuit module, a duplex module and a receiving access module which are connected in sequence, and the uplink power of 2W or higher is achieved on the basis of 0.2W LTE-R;

the LTE-R signal transceiver module is used for transmitting and receiving signals;

the secondary power amplifying circuit module is used for amplifying the power of the circuit;

the duplex module is used for transmitting

The signal and the received signal are isolated, so that the transmitting and receiving can work normally at the same time;

the receiving access module is used for feeding back the received signal to the LTE-R signal transceiver module;

the secondary power amplifying circuit comprises an amplifying link gain control part, a power amplifying circuit part, a power coupling detection part and a power analysis circuit part which are connected in sequence;

the amplification link gain control part is used for carrying out accurate signal intensity control on signals of a preceding stage circuit, preventing distortion and burning, and controlling the gain performance of the whole link;

the power amplifier circuit part is used for amplifying signals;

the power coupling detection part is used for protecting the signal stability of the output end of the power amplifier tube and coupling detection power;

the power analysis circuit part is used for sampling and analyzing the monitored power and feeding back a control command to the amplification link gain control part to adjust the link gain;

further comprising: the first-stage drive amplifier circuit is arranged between the LTE-R signal transceiver module and the second-stage power amplification circuit module and is used for amplifying signals of the circuit and ensuring the linearity of the signals;

the amplification link gain control part comprises an attenuator for adjusting the signal intensity in the circuit;

the duplex module comprises an isolator and a duplexer which are connected in sequence and used for effectively isolating transmitting signals and receiving signals of the circuit.

2. The railway LTE-R wireless communication terminal device of claim 1, wherein the power amplifier circuit part is implemented by LDMOS;

the primary drive amplifier circuit is realized by a POWERCSAS 3PA output module.

3. The LTE-R wireless communication terminal device according to claim 1 or 2, wherein the duplexing module employs a 2W LTE-R duplexer.

4. The railway LTE-R wireless communication terminal device according to claim 1 or 2, wherein the LTE-R wireless communication terminal device adopts FDD-LTE frequency division duplex communication system.